Aluminum and tin base bearing alloy

ABSTRACT

ALUMINUM BASE BEARING ALLOY OF THIS TYPE IS SUITABLE FOR USE AS INTERNAL COMBUSTION ENGINE AND IS SUPERIOR TO CONVENTIONAL ALUMINUM-TIN ALLOYS WITH RESPECT TO THE SURFACE CHARACTERISTICS SUCH AS EMBEDDABILITY AND ANTI-SEIZE CHARACTERISTICS. THIS ALLOY CONTAINS 3 TO 40 WEIGHT PERCENT OF TIN, 0.1 TO 5 WEIGHT PERCENT OF LEAD, 0.1 TO 3 WEIGHT PERCENT OF ANTIMONY AND 0.02 TO 2 WEIGHT PERCENT OF COPPER, THE BALANCE BEING ALUMINUM, THIS ALLOY CAN BE FURTHER MODIFIED EITHER BY OMITTING COPPER, OR BY ADDING 0.02 TO 5% OF ONE OR MORE OF NICKEL, MAGNESIUM, IRON, SILCON AND COPPER IN LIEU OF ACOPPER ADDITIVE OR BY FURTHER ADDING O.01 TO 1 WEIGHT PERCENT OF ONE OR MORE OF TITANIUM, VANDIUM, COBALT AND NIOBIUM.

y 7, 1974 NOBUKAZU MORISAKI 3,809,551

ALUMINUM AND TIN BASE BEARING ALLOY 4 Sheets-Sheet 1 Filed July 16, 1971 QQ EU NQW MQD NEW A b v MWSR qmmlsmk g Q @s Q m9 mm Q Q Q fl IJ QQLG QN W 0707 fiyg) AH ssa/voa/vy INVENTOR BY 4km F'Com s ATTORNEY May 7, 1974 ALUMINUM AND TIN BASE BEARING ALLOY 4 Sheets-Sheet 3 Filed July 16} 1971 A E Q m mbwwmmm mu $3 KER Q9 & an mw QQW SQ WQW MQD KEW C I l llll)O/I 0/X mam/11309 NO/JJ/Hj y 1974 NOBUKAZU MORISAKI ALUMINUM AND TIN BASE BEARING ALLOY 4 Sheets-Sheet 5 Filed July 16, 1971 2&5: V RERQQQ masxfiew N mum m w UN My Q MB mmo \x\ w x m o w u NAM QV x 0/0 vv 1 mm n at y 7, 1 NOBUKAZU MORISAKI 3,809,551

ALUMINUM AND TIN BASE BEARING ALLOY Filed July 16, 1971 4 Sheets-Sheet 4 United States Patent 3,809,551 ALUMINUM AND TIN BASE BEARING ALLOY Nobukazu Morisaki, Nagoya, Japan, assignor to Daido Metal Company Ltd., Nagoya, Japan Filed July 16, 1971, Ser. No. 163,249 Claims priority, application Japan, Nov. 28, 1970, 45/105,328 Int. Cl. C22c 21/00 US. Cl. -75140 3 Claims ABSTRACT OF THE DISCLOSURE Aluminum base bearing alloy of this type is suitable for use as internal combustion engine and is superior to conventional aluminum-tintalloys with respect to the surface characteristics such as embeddability and anti-seize characteristics.

This alloy contains 3 to 40 weight percent of tin, 0.1 to 5 weight percent of lead, 0.1 to 3 weight percent of antimony and 0.02 to 2 weight percent of copper, the balance beingaluminum, this alloy can be further modified either by omitting copper, or by adding 0.02 to 5% of one or more of nickel, magnesium, iron, silcon and copper in lieu of copper additive or by further adding 0.01 to 1 weight percent of one or more of titanium, vanadium, cobalt and niobium. w a

The present invention relates to a bearing alloy and more particularly to an improvement of aluminum-tin bearing alloy.

Aluminum based bearing alloys hithertofore used in bearings of internal combustion engines include such types that have a low percentage of tin (6 to 10% of tin) or that have a high percentage of tin to 40% of tin). The

former type'has a relatively high hardness due to its relatively lowpercentage of tin content so that it has excellent: strength and high fatigue resistance; However, this type of bearing alloy requires a hard shaft and is inferior in surface characteristics such as embeddability and anti-seize characteristics. On the other hand, although the latter type is somewhat inferior to the former type in the strength and fatigue resistance, it can be used with a relatively soft shaft and is superior in surface characteristics such as embeddability and anti-seize. Therefore, the latter type 'has' 'been widely used throughout the world in bearings for high speed and high power internal combustion engines such as in automobile engines. However, recently, there have been rapiddevelopments in engines particularly in automobile engines, and the speed and power of such engines have greatly increased. Thus, even the latter type of aluminum alloy, having relatively high percentages of tin content, has an insuflicient anti-seize characteristic, in view of the thinner lubricant film in high speed internal combustion engines, to say nothing of the former type of aluminumalloy having relatively low percentages of tin content. w

The present invention has a principal object to provide a bearing alloy which is superior to conventional aluminum-tin alloys in surface characteristics such as embeddability and anti-seize characteristics and does not cause seizing even when it is used in high performance internal combustion engines. 1

It has generally been known that lead is soft and effectively improves embeddability when used in a bearing alloy and further it has also been known that the surface characteristics such as anti-seize and embeddability can be improved, by lining lead or lead-tin alloy on an alloy bearing, such as a copper-lead alloy hearing which has inferior anti-seize characteristics. In actual practice, such laminated bearings have been widely used.

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Thus, it has been known that the surface characteristics of anti-seize and embeddability can be improved as compared with a conventional aluminum alloy having a high percentage of tin content by adding lead to an aluminumtin alloy bearing, however, as is apparent from the Al-Pb equilibrium diagram, aluminum and lead do not make a solid solution but provide two separated liquid phases in a molten state, so that it is very difficult to manufacture an almuinum based bearing alloy under normal casting condition. So, it is necessary to employ a special casting technique such as rapid cooling of a molten alloy which is at a sufficiently high temperature under which aluminum and lead are not separated into two liquid phases.

The inventor has discovered the fact that, without using such a special casting technique, it is possible to manufacture under a normal casting condition an aluminumlead alloy in which lead is uniformly and finely dispersed in the aluminum matrix so that the alloy can satisfactorily be used as a bearing metal, simply by adding a suitable amount of antimony. According to the inventors discovery the alloy thus manufactured has improved mechanical properties.

In the accompanying drawings;

FIG. 1 is a diagram showing the relationship between the load and friction coefficient;

FIG. 2 is a diagram showing the relationship between the hardness of alloys and temperature;

FIG. 3 shows the influence of antimony on the tensile strength and elongation of the alloy in accordance with the present invention;

FIG. 4 is a microphotograph showing the structure of the alloy in accordance with the present invention; and

FIG. 5 is a microphotograph showing the structure of a known alloy.

The present invention provides a bearing alloy including 3 to 40 weight percent of tin, 0.1 to 5 weight percent of lead, 0.1 to 3 weight percent of antimony and the balance aluminum or a bearing alloy including 3 to 40 weight percent of tin, 0.1 to 5 weight percent of lead, 0.1 to 3 weight percent of antimony, 0.02 to 2 weight percent of copper and the balance being aluminum. According to the present invention, in place of the copper, one or more of elements selected from the group consisting of copper, nickel, magnesium, manganese, iron and silicon may be added by the amount of 0.02 to 5 percent, so that the mechanical property of the aluminum matrix can be improved. Further, it is within the scope of the present invention to add 0.01 to 1 percent of titanium, vanadium, cobalt and/or niobium for the purpose of degassing or obtaining fine crystals, as is well known in the art.

According to the present invention, by adding lead, the alloy can have an excellent oil-aflinity which is inherent to lead so that, when the alloy is used as a bearing in an internal combustion engine, a suitable lubricant film can be maintained between the bearing and a shaft supported thereby, even during high speed operations, starting and stopping of the engine during which lubricant is normally apt to be interrupted. Thus, the alloy of the present invention is effective in preventing seizure between a shaft and bearing supporting the shaft. Antimony added in accordance with the present invention is effective in ensuring a uniform and fine dispersion of lead in aluminum alloy even in normal casting processes, and it improves the anti-seize characteristics of the alloy as well as the mechanical properties of the aluminum matrix. (Refer to Table 2.)

According to the present invention, the recommended range of lead is 0.1 to 5 weight percent, when there is less than 0.1% of lead present there is no improvement in the anti-seize characteristics of the alloy. Also when the amount of lead exceeds 5 percent, it is very dilficult TABLEl Contents (percent) Contact angle Sn Pb Sb Cu Al (degree Pe a- 1 fittfffz: 3:3

1 Balance.--

Thisinventlon 17 a 2 :As is apparent from Table 1, the contact angle of the alloy in accordance with the present invention is smaller than that of the conventional alloy, This means that the alloy .of the present invention has a greater oil-affinity as compared with'known alloys so that the former is superior to the latter in anti-seize properties. I

As previously described, antimony is effective in making lead finelyand uniformly disperse in an aluminum base metal and also improves the mechanical properties such as. elongation, tensile strength and fatigue resistance of the aluminum matrix in aluminum base bearing alloys. The recommended amount of. antimony is 0.1 to 3 percent in weight and, if the amount of antimony is less than 0.1 percent, it does not provide any noticeable effect, while if the amount exceeds 3 percent, the mechanical properties are adversely affected with the result that elongation is greatly reduced and hardness is increased. (Refer to FIG. 3.)

Tin and copper have commonly been added in an aluminum base bearing alloy and it has been known that tin is effective in reducing the hardness of the alloy and in improving the surface properties such as the embeddability and anti-seize characteristics of bearings made from the alloy thus allowing the use of a soft shaft. If

i of in; .knbwnialuniinum alieyJcon'tain in g high percentage of tin. The experiment has been made by dripping SAE No. 20 oil at a rate of one drop per seven or eight'seconds' at a temperature of 24 C. on a steel disc made of carbon steel for machinery parts (JIS S450) rotating at a speed of 10.27 m./sec. and having a surface roughness of 2 S. Four specimens have been prepared from each material and each specimen had a surface roughness of 1 S FIG. 1 shows the relationship between temperature and the hardness of the alloy in accordancewith the present invention and that of a known aluminum alloy including a high percentage of tin. It will be seen' that the hardness of the alloy of the present invention at the operating temperature of an internal combustion engine, that is about 100 to 150 C. is substantially identical to that of the known aluminum alloy containing 20% of tin at the same temperature, but higher than that of the known aluminum alloycontaining of tin at the same-temperature.

It is understood that the addition of lead isefiecti've in reducing the friction coefficient of the alloy of the" pres ent invention as shown in FIG. 1 and that the addition of antimony is effective in maintaining the hardness of the aluminum matrix so as to prevent softening due tothe addition of lead whereby the hardness of the alloyin' ac"-' cordance with the present invention is maintained at a value substantially identical to that of the known aluminum alloy containing 20% of tin.

Table 2 shows mechanical properties, such as hardness under normal temperature, tensile strength, elongationand bonding property with a steel backing. It will be seen in this table that the alloy of the present invention has substantially the same values as the known alloys do in respect of hardness and tensile strength but it has a greater elongation than the known aluminum alloy containing 30% of tin and substantially the same elongation as the known alloy containing 20% of tinxl urthen-witlr respect to the bonding property; with a-steel backing,- the alloy of the present invention issuperior 'to'the'known' aluminum alloys.

mu -E r Bonding- 1 r0 er,

Contents Hard- Tensile nimvfith ste l ness strength gation b'ackin' Sn Pb v Sb Cu Al (Hv) g-lmmfi) (percent). ,(kalu Known alloys"... 0 Ballance. 31, 11. 5 -30 v 0..... 28 11.0 18 Present invent1on 1 Balance 1120 i; 28

the tin content is less than 3 percent, a 'marked im pro ve-f tion, lead is finely and uniformly dispersed in aluminum due to the addition of antimony. The microst'rnc'ture of the alloy is typically shown in the photograph of FIG. 4.

FIG. 5 shows a typical structure of an alloy which'does not include antimony. In both figures, the structures are shown in X100 magnification. In the structure of the alloy manufactured in accordance with prior art'as' shown in FIG. 5, it will be seen that there are scattered about relatively large spheres 'of lead, however, in thestructure' of the alloy of the present'invention as'shown in FIG. "4,

there is observed a uniformly dispersed structure with no undesirable separation of the lead.

FIG. 2 shows friction coefficient of known aluminum bearing alloy including a high percentage of tin'content and that ofthe alloy in accordance with the present i1i-' vention. As seen in the drawing, the friction coefficient From the stave description, it will be seen that ithefl aluminum alloy of the present invention issubstantially the same as orsuperior to known aluminumalloys in respect of mechanical pr perti'esQbut has improved surface propierties fas anti-seize characteristics due ,to its excellent orlfatfinity and low friction coefiicient. Further, thealuminum alloy of the. present invention has a -high fatigue re sistance, is a very important property as abearing metal. I H a The fatigue resi stance'was tested, by repeatedly applying.

a dynamic torque load. Each specimen was prepared by. bondlng bearing metal to a steel backingby means .of pressure bonding. The inner diameter of the tested bearing was 62 'mm. The lining alloy was 31 mm, wide and 0.3 mm.

thick. The test was perform ed by continuously rotatin shaft. at a speed of' 4'00O r.p.m. under '350 kg./c'm. of j bearing load" applying lubricant-(SAE Ne. 30 oil) under pressure. The fatigue limit was determined'as'the time ,whenfatigue cracks appeared 'j'o'n an area extending to 10:5 of the total bearing inner surface.

As a result of the test, the alum inn alloy of the present, invention, having a composition shown i'n'the Tables l ndj, 2,-had a fatigue limit of 15 hours whilethe fatigue 11m n:

1 'of a 20% tin alloy shown in the'Tables 1 and 2 was jl2, of the loy of the present invention is lower than th t v Q 7 hours and that of 33mm alloy was 10 hours. Thus, the

alloy of the present invention has the best fatigue resistance.

From the aforementioned tests, it will be notice that the alloy of the present invention is substantially same as, or superior to, known alloys in respect of surface property such an anti-seize characteristics and mechanical properties such as fatigue resistance and strength. Therefore, the alloy of the present invention can especially be used in bearings for high speed, high power, internal combustion engines.

What is claimed is:

1. Aluminum based bearing alloy consisting essentially of 0.02 to 2 percent by weight of copper, 5.5 to 40 percent by Weight of tin, 0.1 to percent by weight of lead, 0.1 to 3 percent by weight of antimony, the balance being aluminum.

2. Aluminum based bearing alloy consisting essentially of 5.5 to 40 percent by weight of tin, 0.1 to 5 percent by weight of lead, 0.1 to 3 percent by weight of antimony, 0.02 to 5 percent by Weight of at least one element selected from the group consisting of copper, nickel, magnesium, manganese, iron and silicon, the balance being aluminum on the proviso that content of copper shall not exceed 2 percent by weight.

3. A hearing alloy consisting of about 17 percent tin,

about 3 percent lead, about 2 percent antimony, about 1 percent copper, the balance being aluminum.

References Cited UNITED STATES PATENTS 2,196,236 4/ 1940 Vaders -148 2,284,670 6/1942 McCullough 75138 3,161,502 12/1964 Hunsicker 75143 3,410,331 11/1968 Miller 75138 3,432,293 3/1969 Michael 75138 2,993,783 7/ 1961 Martin 75148 2,196,236 4/1940 Vader's 75-140 2,131,520 9/1938 Nook 75--147 2,184,693 12/1939 Beck 75138 3,551,143 12/1970 Marukawa 75148 2,473,060 6/ 1949 Hunsicker 75140 3,161,502 12/ 1964 Hunsicker 75140 3,205,069 9/ 1965 Wood 75140 HYLAND BIZOT, Primary Examiner US. Cl. X.R. 75147, 148 

